JPS60121701A - Moisture sensitive element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a moisture sensitive element.

[Technical background of the invention and its problems] Moisture sensing element that measures and detects humidity in the atmosphere (humidity sensor)
Up to now, extremely large numbers of d systems have been proposed and put into practical use. In particular, in recent years, various types of humidity sensors that can electrically detect IU temperature and humidity have been proposed. This humidity sensor is attracting attention because it has the feature that not only humidity detection but also humidity control can be easily processed using electrical signals.

By the way, in order to determine the humidity in the atmosphere, the above-mentioned immersion sensor generally physically adsorbs moisture in the atmosphere onto the surface of a humidity sensing element and reads the electrical resistance value.

Conventionally, the humidity sensing element of such a humidity sensor is a sintered body of a polymeric substance, a metal oxide, or a metal oxide baked on a substrate.

However, humidity sensors that use polymeric substances as moisture sensing elements have extremely high resistance values in the low humidity range, ranging from IMΩ to over 10MΩ, so humidity cannot be easily detected using ordinary electrical detection circuits and accuracy is low. The drawback was that it was extremely bad.

In addition, although humidity sensors using metal oxide as a moisture sensing element have excellent initial sensitivity, they all have the drawback of large changes in resistance after long-term use. To overcome this problem, we attached a heater to a humidity sensor made of a sintered body of metal oxide, and temporarily heated the humidity sensing element before measuring humidity, bringing it into a high temperature state and regenerating the surface of the humidity sensing element. There are also known devices that later detect humidity. In other words, the i
By raising the temperature to a high temperature before heating, the moisture-sensitive element is returned to its initial state to ensure reproducibility. However, with such a humidity sensor, continuous humidity detection is impossible because it is necessary to heat the humidity sensor immediately before detecting the humidity. Moreover, a complicated mechanism such as a heater and a heater control circuit is required, which becomes a cause of high cost.

For this reason, Z++0 has recently been used as a humidity sensor.
85-99 mol%, LiZnVO40,5-10%
A device using a moisture-sensitive element body made of a metal oxide having a composition of k% and cr2oa+FezO80.5-5 moles has been developed (Japanese Patent Application Laid-Open No. 56-4204). This humidity sensor is suitable for high-quality treatment i11! It can be used stably for a long period of time under normal environmental conditions (0 to 40℃ - 130 to 90% RH) with low resistance, and is fully applicable to humidity control in air conditioners and humidifiers. can. However, when using a humidified humidity sensor under high temperature conditions, 1. In some cases, sufficient aging characteristics and reproducibility could not be obtained.

[Objective of the Invention] The present invention provides a moisture-sensitive element that can be used stably with almost no change in resistance even when used for a long time under high-temperature conditions, and has an electrical resistance value that is easy to use even in a wide range of humidity. This is what we are trying to provide.

[Summary of the invention] The present invention comprises Crp+0821-73 mol %, 25-55 mol % of at least one of Zn□ and MgO,
CuO0,5-8,0 mol%, ViOII O,
This is a moisture-sensitive element comprising a pair of electrical conductors in a sintered body containing 0.5-8.0 mol% of at least one of 5-8.0 mol %, Nano, and 20 O as an essential component.

For example, such a humidity sensing element may be used at an ambient temperature of 25°C and a relative humidity of 3.
In the case of 0%, it is approximately 500Ω, and the relative humidity is 9 at the same temperature.
In the case of 0-chi, it has a resistance value of about 10 Ω, which is easy to use in a wide range of humidity, and has high reliability with little change over time even when left at a high temperature of 85° C. for a long period of time. As described above, the reason why the moisture sensitive element of the present invention has excellent characteristics is that a small amount of Crz08. ZnO etc. and CuO.

It is presumed that this is because VgOJ has a structure in which at least one type of component exists among Na2O and KgO.

The reason for limiting the blending ratio of Crg08 is that if the amount is less than 21 momoles, the resistance value as a moisture-sensitive property will increase overall, but if the amount exceeds 73 momoles, it will not be possible to leave it at high temperatures. This is because the change over time becomes large.

The reason for limiting the blending ratio of at least one of the above ZnO and MgO is that if the amount is 25 mmol, the change over time will be large when left at high temperatures, but if the sardine exceeds 55 mmol. This is because the resistance value as a moisture-sensitive characteristic becomes higher overall.

In this case, the same effect can be exerted even if ZnO and MgO are used alone or together once a month.

The reason for limiting the blending ratio of CuO is that the amount is 0.
If it is less than 5 mol, the change over time when left at high temperature becomes large, but if t exceeds 8.0 mol,
This is because the sensitivity on the low humidity side is manipulated.0 At least one of the above V2O6, NaaO and KgO
The reason for limiting the mixing ratio of each species is V1106. Na
When at least one of 2O and 20 is each less than 0.5 molar amount, the resistance value as a moisture sensitive property increases overall, but V2O5, Nano and Kz
The amount of at least one of O is 8. This is because when the θ molar range is exceeded, the change over time when left at high temperatures increases.0 [Embodiments of the Invention] Next, the present invention will be described in detail.

Example 1 First, the starting materials are chromium oxide and heat exchanger.

Fine powders of copper oxide, vanadium oxide, sodium carbonate, and potassium carbonate were used. These starting materials were converted into Cr1Ibs
, ZnO, Cub, V2O5, Na1IO, KzO
The molar ratio is 44%.

The mixture was weighed to give 44%, 4%, 4%, 2%, 2%, and then mixed in a pot mill for 24 hours. After drying this mixture at 120°C for 12 hours,
It was calcined at 00°C. Subsequently, the calcined product was pulverized 24 hours a day in a bot mill, and then dried again at 120'''C for 12 hours to prepare a raw material powder.

Next, polyvinyl alcohol (binder) is added to the raw material powder for 2 hours, granulated using a Leica machine, and the granulated product is pressure-molded at 500 Ky/ca to form IHH2O2.
xnz, a disk-shaped molded body with a thickness of about 2 ms was made.

Next, this molded body was heated at a temperature of 1300°C for 2 hours, and both main surfaces of the sintered body were polished to a thickness of IMM.
And so. Subsequently, oxidized ruthenium paste was applied between both sides of this sintered body (moisture-sensitive element body) and baked at 9, C, 1700"C with a screen stamp to form a 7 mm diameter square. A moisture-sensitive element having the structure shown in Fig. 1 was manufactured.In addition, 1 in Fig. 1 is the humidity-sensitive element body 52Id''jl, 4f+1.

Therefore, for the 6-humidity element of Example 1, the resistance values (M'+r!+i! characteristics) of 11 were investigated with the ambient temperature kept constant at 25°C and the relative humidity varied from 30 to 90q6. As a result, a Qlj characteristic diagram shown in Figure 812 was obtained. This second
As is clear from the figure, the humidity sensing element of the present invention has an ambient temperature of 25°C.
under.

A 14z1 Humidity 30 Ω, same temperature 〃° (bottom,
It can be seen that at a relative humidity of 90%, the resistance value is 7Ω, a low resistance value that is extremely easy to use in a wide temperature range.

In addition, after leaving the humidity sensing element of Example 1 in a bath at a temperature of 85°C for 1000 hours, the resistance value (EV humidity) when the relative humidity was varied from 30 to 90 at an ambient temperature of 25°C was When the characteristics were investigated, the characteristic diagram shown in Fig. 3 was obtained.It is clear from this Fig. 3 that the SI! damage of the arm after leaving the humidity sensing element of the present invention at high temperature has almost no change. It can be seen that it has stable characteristics over time.

Examples 2 to 13 Twelve types of humidity sensing elements each having a sintered body (moisture sensing element) having the composition shown in Table 1 below were manufactured in the same manner as in Example 1.

Therefore, the humidity sensing elements of Examples 2 to 3 were subjected to an ambient temperature of 25°C, a relative humidity of 30%, a resistance value of 90% (initial moisture sensitivity characteristics), and were left in an 85°C lagoon for 1000 hours. After the ambient temperature is 25°C, relative humidity is 30°C, 90°C.
% resistance value (moisture sensitivity characteristics after being left at high temperature) was investigated. The results are also listed in Table 1. In addition, in Table 1, reference examples 1 to 12 include humidity-sensitive elements equipped with moisture-sensitive elements outside the composition range of the present invention. It can be seen that the humidity sensing element has a resistance value that is extremely easy to use in a wide range of humidity, and also has stable aging characteristics even under high temperature conditions. In contrast, a moisture-sensitive element made of a sintered body outside the composition range of the body invention (Reference Example 1
~12) do not satisfy both of the above-mentioned resistance value that is easy to use in a wide range of humidity and stable aging characteristics under high temperature conditions.

Example 14 First, chromium oxide, magnesium carbonate, steel oxide, vanadium oxide, and sodium carbonate are used as starting materials.

Fine powder of potassium carbonate was used. These starting materials are Cr
2O5, MgO, Cub, VzOIi, Na2O,
K2O(7)% #ratio-r 44%.

The mixture was weighed to give 44 g, 41%, 4 v, 2 g, and 2 g, and then mixed 24 hours a day in a bot mill.

Subsequently, this mixture was dried at 120'C for 12 hours and then calcined at 800C. Subsequently, the calcined product was pulverized 24 hours a day in a bot mill, and then dried again at 120° C. for 12 hours to prepare a raw material.

Next, a moisture sensing element having the same structure as that shown in FIG. 1 was manufactured using the above raw material powder in the same manner as in Example 1. When the resistance value (humidity sensitivity characteristic) was investigated when the relative humidity was changed from 30 to 90 degrees, the characteristic diagram shown in FIG. 4 was obtained. As is clear from FIG. 4, the humidity sensing element of the present invention has a
It can be seen that at the same temperature and relative humidity of 90 degrees, it shows a low resistance value of 8 Ω, which is extremely easy to use in a wide humidity range.

In addition, the humidity sensing element of Example 14 was left in a constant temperature bath at a temperature of 85°C for 1000 hours and 1111 hours, and the ambient temperature was 25°C.
Resistance value when relative humidity layer is changed from 30 to 90% at °C (
When the moisture sensitivity characteristics were investigated, the characteristic diagram shown in FIG. 5 was obtained. As is clear from FIG. 5, the moisture-sensing characteristics of the humidity-sensing element of the present invention after being exposed to several high temperatures did not change much.
It can be seen that it has stable characteristics over time.

5th to 26th Preparation of the Month Twelve types of humidity sensing elements having sintered bodies (humidity sensing elements) having the compositions shown in Table 2 below were manufactured in the same manner as in Example 1.

Therefore, the humidity sensing elements of Examples 15 to 26 were tested at an ambient temperature of 25°C, a relative humidity of 30°C, a resistance value of 90% (initial moisture sensitivity characteristics), and after being left in a constant temperature bath at 85°C for 1000 hours. ambient temperature 25℃, relative humidity 30%, 90%
The resistance value (moisture sensitivity characteristics after being left at high temperatures) was investigated. The results for sheep are also listed in Table 2. In addition, in Table 2, reference examples 13 to 24 also include moisture-sensitive elements having moisture-sensitive elements that deviate from the composition range of the present invention.

As is clear from Table 2 above, the humidity sensing element of the present invention has a resistance value that is extremely easy to use in a wide temperature range, and has stable aging characteristics even under high temperature conditions. On the other hand, moisture sensing elements (Reference Examples 13 to 24) made of sintered monoliths outside the composition range of the present invention have a resistance value that is easy to use in the wide range of humidity and stable aging characteristics under high temperature conditions. Don't satisfy both.

Examples 27 to 31 In the same manner as in Example 1, a 5-inch moisture-sensitive element having a sintered body (moisture-sensitive element) having a composition shown in Table 3 below was manufactured.

Therefore, for the humidity sensing element of Examples 27 to 3, the circumference was 8.
Temperature: 25°C, relative humidity: 30%, 90cm resistor (
(initial moisture sensitivity characteristics), as well as in a constant temperature bath at 85°C.

The resistance values (humidity sensitivity characteristics after being left at high temperatures) at an ambient temperature of 25° C. and a relative humidity of 30 and 90 degrees after being left for a period of time were investigated.

The results are also listed in Table 3. Further, in Table 3, moisture sensitive elements having moisture sensitive elements outside the composition range of the present invention are also listed as Reference Examples 25 to 26.

As is clear from Table 3 above, the humidity sensing element of the present invention has a resistance value that is extremely easy to use in a wide range of humidity, and has stable aging characteristics even under high temperature conditions. On the other hand, the humidity sensing elements (Reference Examples 25 to 26) made of sintered bodies outside the composition range of the present invention have resistance values that are easy to use in the wide range of humidity and stable aging characteristics under high temperature conditions. Does not satisfy both [Effects of the Invention] As detailed above, the present invention has an electrical resistance value (humidity sensitivity) that is easy to use even in a wide range of humidity, and can be used for long periods of time under high temperature conditions. It is possible to provide a highly reliable moisture sensing element that can be stably used with almost no change in resistance value even at °C.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one form of the moisture-sensitive element of the present invention, and FIG.
The figure is a diagram showing the initial moisture sensitivity characteristics of the humidity sensing element of Example 1, and FIG. 3 is the high temperature number fR of the humidity sensing element of Example 1.
Figure 4 is a diagram showing the initial moisture sensitivity characteristics of the humidity sensing element of Example 14; Figure 5 is a diagram showing the initial humidity sensitivity characteristics of the humidity sensing element of Example 14; FIG. 2 is a diagram showing the moisture sensitivity characteristics of 1...Sintered body (moisture sensitive element) 2...1@1w Agent Patent attorney Noriyuki Chika (and 1 other person) No. 1 Figure 2 Cause, 30 hD 70 '10 Ome Sakai 4 pieces degree (%) Fig. 30 Old o 7 o q. Relative 1 cliff tX> Figure 4, 30! so 7oγO humidity S (%) Fig. 5, 30

Claims (1)

[Claims] CrwOIJ 21-73 Mok%, ZnO and HiNg(M)! ll small〈7mo1 type 25-55mo+%+C
uOO, 5-8,0-EA/%. V2O50.5~8.0%, NaBO and (
fi K,y:! 1. A moisture-sensitive element comprising a pair of electrodes on a sintered body having an essential composition of 0.5 to 8.0 mol.